1. Field of the Invention
The field of the invention is balanced doors of the type wherein a door is mounted to pivot around a medially disposed guide roller so that a hinge side portion of the door swings inwardly from the door frame while a latching side portion of the door swings outwardly from the door frame.
2. Description of the Prior Art
A manually operable balanced door is disclosed in Catlett et al, U.S. Pat. No. 3,605,399, issued Sept. 20, 1971. The operability, reliability and maintainability of this balanced door can be improved if the hardware for mounting a door within a door frame is reconfigured in several important respects.
In the prior construction the balanced door is mounted in a doorway by an upper door pivot arm and a lower door pivot arm that are coupled to a hinge side portion of the door to form a vertical pivot axis for the door. A guide track is mounted on a downwardly facing side of a header and a cylindrical guide roller is mounted on a top leaf of the door and is received in the guide track to form a pivot that moves within the door frame. A door closer is disposed within the header so that a pivotable check shaft on the closer is disposed on the latching side of the door frame. A linkage mechanism within the header couples the check shaft to the hinge end of the upper door pivot arm so that the closer applies a rotational force to the upper pivot arm at that point.
The prior arrangement has not been entirely satisfactory, because the door closer does not exert enough control on the door in the 70.degree.-90.degree. range of door-opening swing. In addition, the operating forces that must be applied to the hinge end of the upper pivot arm to restrict the opening of the door, or to return the door to its closed position, are greater than desired, due to the lack of leverage available at the hinge end of the upper pivot arm. Thus, an improvement in the arrangement of the door closer and its linkage mechanism has been sought to improve the operation of the door in the 70.degree.-90.degree. range and provide greater durability for the balanced door assembly.
This prior construction also does not allow convenient disassembly of the door from the door frame for maintenance or replacement of door hardware. This can be seen from considering the prior arrangement in the area of the hinge pin at the hinge end of the upper pivot arm. This hinge pin projects upwardly from the hinge end of the upper pivot arm into an annular bearing that is retained in a race mounted in the upper corner of the door frame level with the header. This was necessary in the prior construction because space along the upper hinge pin had to be reserved to couple the door closer linkage. This arrangement was unsatisfactory, however, when the door had to be removed, because the upper hinge pin and bearing assembly were relatively inaccessible in the upper corner of the door frame.